C. 4 or more d.3 geometry math question

After the seventh month of a 12-month loan: the numerator is: {(n + 11) + (n + 10) + (n + 9) + (n + 8) + (n + 7) + (n + 6) + (n + 5)} = , and the denominator is: {(n) + (n + 1) + + (n + 11)} = . therefore, the fraction is numerator/denominator (to the nearest tenth) = %

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

Can someone tell me if these are correct?